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Redescription of Cearadactylus atrox (Pterosauria,
Pterodactyloidea) from the Early Cretaceous Romualdo
Formation (Santana Group) of the Araripe Basin, Brazil
a
b
c
Bruno C. Vila Nova , Juliana M. Sayão , Virgínio H. M. L. Neumann & Alexander W. A.
Kellner
d
a
Laboratório de Paleontologia, Departamento de Biologia, Faculdade de Filosofia, Ciências
e Letras de Ribeirão Preto, Universidade de São Paulo (USP), Avenida Bandeirantes 3900,
Monte Alegre, 14040-901, Ribeirão Preto , São Paulo , Brazil
b
Laboratório de Biodiversidade do Nordeste, Núcleo de Biologia, Centro Acadêmico de
Vitória Universidade Federal de Pernambuco (UFPE), Rua do Alto do Reservatório s/n, Bela
Vista, 52050-480, Vitória de Santo Antão , Pernambuco , Brazil
c
Laboratório de Geologia Sedimentar e Ambiental, Departamento de Geologia, Centro de
Tecnologia e Geociências, Universidade Federal de Pernambuco (UFPE), Av. Acadêmico Hélio
Ramos s/n, Cidade Universitária, 50740-530 , Recife , Pernambuco , Brazil
d
Laboratório de Sistemática e Tafonomia de Vertebrados Fósseis, Departamento de Geologia
e Paleontologia, Museu Nacional, Universidade Federal do Rio de Janeiro (UFRJ), Quinta da
Boa Vista s/n, São Cristóvão, 20940-040, Rio de Janeiro , Rio de Janeiro , Brazil
Published online: 07 Jan 2014.
To cite this article: Bruno C. Vila Nova , Juliana M. Sayão , Virgínio H. M. L. Neumann & Alexander W. A. Kellner (2014)
Redescription of Cearadactylus atrox (Pterosauria, Pterodactyloidea) from the Early Cretaceous Romualdo Formation (Santana
Group) of the Araripe Basin, Brazil, Journal of Vertebrate Paleontology, 34:1, 126-134
To link to this article: http://dx.doi.org/10.1080/02724634.2013.793694
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Journal of Vertebrate Paleontology 34(1):126–134, January 2014
© 2014 by the Society of Vertebrate Paleontology
ARTICLE
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REDESCRIPTION OF CEARADACTYLUS ATROX (PTEROSAURIA, PTERODACTYLOIDEA)
FROM THE EARLY CRETACEOUS ROMUALDO FORMATION (SANTANA GROUP) OF THE
ARARIPE BASIN, BRAZIL
BRUNO C. VILA NOVA,*,1 JULIANA M. SAYÃO,2 VIRGÍNIO H. M. L. NEUMANN,3 and ALEXANDER W. A. KELLNER4
1
Laboratório de Paleontologia, Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto,
Universidade de São Paulo (USP), Avenida Bandeirantes 3900, Monte Alegre, 14040-901, Ribeirão Preto, São Paulo, Brazil,
[email protected];
2
Laboratório de Biodiversidade do Nordeste, Núcleo de Biologia, Centro Acadêmico de Vitória Universidade Federal de
Pernambuco (UFPE), Rua do Alto do Reservatório s/n, Bela Vista, 52050-480, Vitória de Santo Antão, Pernambuco, Brazil,
[email protected];
3
Laboratório de Geologia Sedimentar e Ambiental, Departamento de Geologia, Centro de Tecnologia e Geociências, Universidade
Federal de Pernambuco (UFPE), Av. Acadêmico Hélio Ramos s/n, Cidade Universitária, 50740-530, Recife, Pernambuco, Brazil,
[email protected];
4
Laboratório de Sistemática e Tafonomia de Vertebrados Fósseis, Departamento de Geologia e Paleontologia, Museu Nacional,
Universidade Federal do Rio de Janeiro (UFRJ), Quinta da Boa Vista s/n, São Cristóvão, 20940-040, Rio de Janeiro, Rio de Janeiro,
Brazil, [email protected]
ABSTRACT—Based on one of the first cranial pterosaur specimens unearthed from the Romualdo Formation (Araripe
Basin), Cearadactylus atrox has caused disagreement among paleontologists regarding its relationships. Ranging from an
ornithocheirid, an indeterminated pterodactyloid, to a ctenochasmatid, some authors even regarded this species as representing a distinct suprageneric clade. Further preparation of the holotype that was transferred to the collections of the Museu
Nacional/UFRJ (MN 7019-V) revealed several new features allowing a redescription and reevaluation of the phylogenetic
position of this species. Among the new observations, it is clear that the rostral end of this specimen had been glued to the
skull, rendering previous anatomical interpretations incorrect. There is no rostral gap, and the expanded rostral end of the
premaxillae is larger than the dentary, rather than smaller. Cearadactylus atrox is here considered a valid taxon that can be
diagnosed by a dentary groove that bifurcates at the rostral end, orbit and naris in a high position relative to the nasoantorbital fenestra, and a comparatively small number of teeth (32–36 maxillary, 22–26 mandibular), decreasing in size towards the
posterior end. Phylogeneticaly, it is placed as the sister group of the Anhangueridae, forming a large clade of Brazilian forms
(Tropeognathus and Anhanguera), which has a European taxon (‘Ornithocheirus’ compressirostris) as its sister group.
SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP
INTRODUCTION
During the past 40 years the Araripe Basin has yielded some of
the best-preserved pterosaur material found so far (e.g., Kellner,
2006). These specimens were unearthed from the Romualdo Formation, which is regarded as Aptian/Albian in age (Pons et al.,
1990). Many of the formally described taxa from this deposit have
been included in phylogenetic analyses (e.g., Kellner, 2003), aerodynamic and biomechanical studies (Costa et al., 2010; Palmer
and Dyke, 2012), ecological studies (Martill, 2007; Vila Nova
et al., 2011; Sayão et al., 2012), and morphometric analyses (Vila
Nova and Sayão, 2012). Some even revealed the presence of exceptionally well-preserved soft tissue (Martill and Unwin, 1989;
Kellner, 1996).
One of the first species described from this basin was Cearadactylus atrox, which is based on an almost complete skull (lacking the occipital region and the braincase) and an occluded lower
jaw. First mentioned in an abstract by Leonardi and Borgomanero (1983), the species was formally described 2 years later
(Leonardi and Borgomanero, 1985).
Since its description, the systematic position of C. atrox
has been disputed. First, Leonardi and Borgomanero (1983)
*Corresponding
author.
referred this taxon to the Ornithocheiridae, but later regarded
it as a pterodactyloid of unknown affinities (Leonardi and
Borgomanero, 1985). In a popular review of the Pterosauria,
Wellnhofer (1991) erected the family Cearadactylidae, comprising only Cearadactylus atrox. Reviewing part of the pterosaur
fauna of the Araripe Basin, Kellner and Tomida (2000) considered this species a member of the Pteranodontoidea, closely
related to the anhanguerid clade. More recently Unwin (2002)
referred Cearadactylus atrox to the Ctenochasmatidae and
questioned the allocation of Cearadactylus? ligabuei, described
by Dalla Vecchia (1993), to that genus, stating that Cearadactylus
should be limited to the type species (i.e., Cearadactylus atrox).
Initially part of the Borgomanero collection (F-PV-93;
Leonardi and Borgomanero, 1985), this material was kindly donated by Ragnhild Borgomanero to the Museu Nacional/UFRJ
(Rio de Janeiro, Brazil; MN 7019-V), after her husband, Dr.
Guido Borgomanero, passed away.
In 2009, this specimen was fully prepared by one of the authors
(B.C.V.-N.), and it became clear that the rostral end had been
broken and glued back in an inversed position. Furthermore,
this detailed preparation showed that several anatomical features
were incorrectly described. Here we provide a detailed redescription of the holotype and only known material of C. atrox, and discuss its phylogenetic position within the Pterodactyloidea, testing
previous hypotheses.
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VILA NOVA ET AL.—REDESCRIPTION OF CEARADACTYLUS ATROX
127
The Romualdo Formation (Fig. 1) is composed of overlapping layers of shales, marls, and limestones (Assine, 2007),
and has an extensive history of fossil discoveries (e.g., Maisey,
1991). Among the most interesting vertebrates are pterosaurs
and fishes, whereas other tetrapods are less common (e.g., Bittencourt and Langer, 2011, 2012). The majority of fossils are found
in carbonate concretions (Fara et al., 2005), which are responsible for the exquisite preservation (e.g., Saraiva et al., 2007), contrary to most other occurrences, where specimens are either very
fragmentary or flattened (e.g., Wellnhofer, 1991; O’Connor et al.,
2011).
SYSTEMATIC PALEONTOLOGY
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PTEROSAURIA Kaup, 1834
PTERODACTYLOIDEA Plieninger, 1901
PTERANODONTOIDEA sensu Kellner, 2003
CEARADACTYLUS ATROX Leonardi and Borgomanero,
1985
(Figs. 3–6)
FIGURE 1. Location map of the Araripe Basin and main cities. There is
no further information regarding the provenance of the specimen (after
Sayão et al., 2011).
GEOLOGIC SETTING
The origin of the Araripe Basin is related to the separation
of the South American and African continents, and the opening
of the South Atlantic Ocean (Neumann and Cabrera, 1999). The
stratigraphic arrangement of the deposits in the basin has been a
subject of controversy, with many different (and sometimes conflicting) proposals (Martill, 2007). Here we follow Valença et al.
(2003), who elevated the former Santana Formation to a group
and its three members, from the older to the younger, the Crato,
Ipubi, and Romualdo members, to formation status.
Emended Diagnosis—Large pteranodontoid pterosaur with
the following autapomorphies: dentary groove reaching the rostral tip of the bone, with a bifurcated end; posterior and ventral
limits of the nasoantorbital fenestra forming a right angle. It can
be further distinguished from other pteranodontoids by the following combination of characters: orbit and naris above the middle of the nasoantorbital fenestra; comparatively small number
of teeth (16–18 maxillary, 11–13 mandibular on each side); teeth
decreasing in size towards the posterior end.
Description—The holotype of C. atrox (MN 7019-V) is an almost complete skull, lacking the occipital region and braincase. It
is anteroposteriorly elongated, with a preserved length of 515 mm
(Fig. 2). Although preserved three-dimensionally, the specimen
shows some lateral distortion, with a few cranial elements displaced from their original anatomical position, including the right
quadrate, which is below the dorsal margin of the nasoantorbital
fenestra. The bone surface of the right side is not well preserved
and shows signs of erosion due to weathering prior to collection.
The lower jaw was isolated from the skull, allowing observation
of the palate (Fig. 3). There are two fractures, one in the rostrum
and another in the occipital region. These were restored using a
resin paste (prior to being deposited in the museum’s collection),
which was also used in the reconstruction of the rostral teeth, increasing their sizes and creating an artificial appearance that did
not match the original anatomy of the skull. A small fragment of
the rostral portion contact with the rest of the skull is missing.
During preparation, it became clear that the rostral portion was
glued back to the remaining part of the skull inverted, with the
FIGURE 2. Cearadactylus atrox holotype (MN 7019-V) before final preparation, as described by Leonardi and Borgomanero (1985). Scale bar equals
100 mm.
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JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 34, NO. 1, 2014
FIGURE 3. A, holotype of Cearadactylus atrox (MN 7019-V) after preparation in left lateral view. The rostral portion was broken, and is shown in
the correct position; B, sketch of Cearadactylus atrox, showing the preserved bones. Abbreviations: ang.r, angular (right); art.l, articular (left); art.r,
articular (right); d, dentary; j, jugal; la, lacrimal; m, maxilla; ms, mandibular symphysis; np, nasal process; pm, premaxilla; q.l, quadrate (left); q.r,
quadrate (right). Scale bar equals 100 mm.
lower jaw attached to the maxilla and the premaxillae-maxillae
connected with the dentary. The dentary groove, which starts anterior to the rostral fracture, reaches the tip of the lower jaw. The
palatal ridge also starts anterior to the fracture ending at the rostral tip of what was thought to be the dentary, confirming this
inversion. This artificial appearance misled authors regarding the
anatomy of this species.
As typical for the Pterodactyloidea, the nasoantorbital opening occupies a considerable portion of the skull, reaching around
38% of the preserved length, being estimated to occupy about
one-third of the length between the squamosal and the rostral tip
of the premaxilla. It reaches the 13th alveolus, and forms an almost straight angle with the posteroventral corner of the jugal,
differing from the obtuse angle seen in Anhanguera and ‘Or-
nithocheirus’ compressirostris (Kellner and Tomida, 2000; Andres and Ji, 2008).
The premaxilla is the main bone in the upper rostral portion,
and reaches the dorsorostral margin of the nasoantorbital fenestra. However, its caudal end is not preserved, being at least
330 mm long. In left lateral view, the contact between the premaxilla and maxilla is delimited by a shallow groove. The remnant of a small sagittal crest is seen in the dorsal surface of the
premaxilla, extending from the rostral tip to at least the 5th premaxillary alveolus (Fig. 4), indicating that Cearadactylus had such
a cranial structure, contrary to previous descriptions (Leonardi
and Borgomanero, 1985; Wellnhofer, 1991; Dalla Vecchia, 1993;
Kellner and Tomida, 2000; Fastnacht, 2001; Unwin, 2002; Veldmeijer, 2003).
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VILA NOVA ET AL.—REDESCRIPTION OF CEARADACTYLUS ATROX
129
FIGURE 5. A, rostral portion of the Cearadactylus atrox premaxilla in
ventral view; B, sketch of the same, with palatal ridge indicated. Abbreviation: prid, palatal ridge. Scale bar equals 10 mm.
FIGURE 4. A, rostral portion of the Cearadactylus atrox premaxilla in
right lateral view; B, sketch of the rostral portion, where the basis of the
premaxillary sagittal crest is indicated. Abbreviation: pmcr, premaxillary
crest. Scale bar equals 10 mm.
In ventral view, the premaxilla shows an elevation (palatal
ridge) starting at the rostral fracture, which continues caudally
until the middle portion of the palate (Fig. 5), similar to other
anhanguerids (Wellnhofer, 1987; Kellner and Tomida, 2000). It
is smoother than the one present in Tropeognathus mesembrinus,
and disappears near the nasoantorbital fenestra.
The maxilla represents most of the ventral surface of the
skull, a common feature within pterodactyloids. The right one is
incomplete, with only a fragment preserved close to the nasoantorbital fenestra. The alveoli are not well preserved, and it is difficult to confirm their exact number, but around 16 alveoli are
identified on the left side (only two with teeth). They extend until the midlength of the nasoantorbital fenestra.
All bones related to the braincase and upper part of the nasoantorbital fenestra are lacking, except for the process of the
nasal, which is displaced inside this fenestra. This process is essentially a thin, well-developed bone blade that almost reaches
the ventral surface of the skull, different from the reduced structure seen in the Tapejaridae and Azhdarchidae, but similar to
that in the Anhangueridae (Kellner and Langston, 1996; Kellner
and Tomida, 2000; Kellner, 2004). At least in the preserved portion, it lacks foramina, contrary to the condition observed in Anhanguera piscator and A. santanae (Kellner and Tomida, 2000).
Although incomplete, the jugal forms the lower margins of the
orbit and the lower temporal fenestra. Its suture with the quadra-
tojugal is not discernible, and together with the quadrate, these
bones form a single fused structure. The rostral ramus of the jugal narrows rostrally and ends as a thin bone plate.
As pointed out before, the right quadrate was displaced underneath the left. Its posterior region connects with a long and thin
prolongation of the bone, forming the helicoidal structure seen in
many pterodactyloids (e.g., Campos and Kellner, 1985; Bennett,
2001).
The lower jaw is almost complete. The right side has most
of the external surface badly preserved. Some jaw elements are
displaced, and the surangulars cannot be observed. Most ornithocheiroids with a premaxillary sagittal crest also show a dentary crest, as seen in Anhanguera and Tropeognathus; on the contrary, C. atrox does not possess any trace of a dentary sagittal
crest, being in this respect similar to Brasileodactylus (Kellner,
1984; Sayão and Kellner, 2000). The dentaries are nearly complete and slightly compressed, forming most of the jaw. They
are fused into a large symphysis, which is 110 mm long, occupying about 20% of the total jaw length. This condition is similar
to Tropeognathus, but smaller than in Anhanguera (Wellnhofer,
1987; Kellner and Tomida, 2000). A medial groove is present
and reaches the distal extremity of the dentaries, as observed in
Brasileodactylus (Kellner, 1984; Sayão and Kellner, 2000; Veldmeijer et al., 2005). In C. atrox, however, this groove does bifurcate at the rostral tip, differing from that in Brasileodactylus
araripensis (Fig. 6).
The symphysis bears six alveoli on each side, with teeth in the
1st, 3rd, and 5th alveoli of the left side. Five more alveoli are
present anterior to the anterior margin of the left nasoantorbital
fenestra, totaling 11 teeth on each side of the lower jaw. The angulars are thin bones, not fused to the dentaries, and are displaced
from their original positions. Due to the taphonomy, they are
positioned between the lower jaw and the maxilla, and the right
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JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 34, NO. 1, 2014
the rostral fracture could bear one or at most two pairs of alveoli,
so we state the dental formula of C. atrox as 16–18 maxillary teeth
per side and 11–13 in each dentary.
In both the maxilla and dentary, the first four pairs of teeth
are larger than the others, but they are smaller than previously
thought (Leonardi and Borgomanero, 1985; Unwin, 2002). The
3rd tooth measures 35 mm in height, whereas from the 6th alveolus to the posterior end the teeth reach around 10 mm. The
left upper 8th and 16th alveoli, as well as the left lower 5th and
11th show replacement teeth. The dentition gradually decreases
in size posteriorly. This differs from the condition in Anhanguera,
in which the 5th and 6th teeth are smaller than the 4th and 7th
(Wellnhofer, 1977, 1985, 1991; Wellnhofer et al., 1983; Kellner,
1984, 2003; Kellner and Tomida, 2000).
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PHYLOGENETIC ANALYSIS
FIGURE 6. A, Cearadactylus atrox rostral portion of the dentary in dorsal view; B, sketch showing the bifurcated end of the groove. Abbreviations: al, alveolus; dg, dental groove; ms, mandibular symphysis. Scale bar
equals 30 mm.
angular is partially displaced to lie inside the nasoantorbital
fenestra.
The left articular is firmly connected to the dentary, but the
suture between them is still evident. The right articular is displaced medially, with the rostral tip absent. Due to the position
and thickness of this bone, it is possible to assume that it reached
beyond the regions corresponding to the nasoantorbital fenestra.
Rostrally, the articular extends as a long and thin element until
at least the 10th dentary alveolus.
The rostral teeth are elongated, thin, and slightly curved posteriorly, and directed somewhat forward and outward. Starting
from the 6th tooth, the teeth become smaller, more vertical, and
straighter, so that they are less curved toward the posterior region. Many alveoli are damaged, and only three dentary and
seven premaxillary alveoli bear teeth. We identified 16 maxillary
alveoli in the left side and 11 in the dentary. The portion lost from
In order to establish the phylogenetic position of C. atrox (MN
7019-V), we used three different published matrices (Andres and
Ji, 2008; Wang et al., 2009; Lü et al., 2010; see Suplementary
Data for characters scores). All matrices were analyzed using the
same parameters as used by the original authors, with heuristic
searches implemented in the programs PAUP∗ 4.0b10 (Swofford,
2003) and TNT version 1.0 (Goloboff et al., 2008). Resampling
was conducted with bootstraps and jackknifing, with 1000 replicates for each data set, and Bremer index support was calculated
for each consensus tree.
The analysis using the data set of Andres and Ji (2008) resulted
in 334 most parsimonious trees (MPTs). The heuristic search
placed C. atrox in a polytomy with the Anhangueridae (sensu Andres and Ji, 2008), a clade consisting of Tropeognathus mesembrinus, Liaoningopterus gui, Anhanguera blittersdorffi, A. santanae,
and A. piscator (Fig. 7), with ‘Lonchodectes’ (or ‘Ornithocheirus,’
according to which author is followed) compressirostris as its sister group. This result was previously recovered by Sayão et al.
(2012) and the addition of C. atrox did not result in any change
to their tree topology. The main characteristics that separate C.
atrox from the Anhangueridae are as follows: lack of a dentary
sagittal crest (character 45) and the posteroventral limit of the nasoantorbital fenestra forming a right angle (character 8; differing
from the more rounded and concave condition in Anhangueridae).
The majority consensus tree published by Lü et al. (2010) recovered Cearadactylus as a member of the Ctenochasmatidae,
probably as a result of incorporating the previous anatomical
interpretations (and scoring) of Unwin (2002). By rescoring C.
atrox in this data set, we recovered a different result. The search
conducted with TNT found 392 MPTs (Fig. 8). The majority consensus tree of this analysis placed C. atrox within Ornithocheiri-
FIGURE 7. Detail of the strict consensus
tree of 334 MPTs showing the position of C.
atrox using the Andres and Ji (2008) data
set and clade names. A, Pteranodontoidea;
B, Istiodactylidae; C, Anhangueridae. Upper
values are bootstraps and lower figures are
jackknife values. Consistency index = 0.486
and retention index = 0.808 for the consensus
tree.
VILA NOVA ET AL.—REDESCRIPTION OF CEARADACTYLUS ATROX
131
FIGURE 9. The putative phylogenetic position of Cearadactylus atrox
based on the Lü et al. (2010) data set, according to Unwin (2002). These
relationships are changed here, due to new character data available from
the more fully prepared holotype.
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FIGURE 8. Detail of the majority consensus tree of 392 MPTs showing the position of C. atrox using the modified Lü et al. (2010) data set.
A, Istiodactylidae; B, Ornithocheiridae. Upper values are bootstraps and
lower are figures are jackknife values. Consistency index = 0.434 and retention index = 0.798 for the consensus tree.
dae as the sister group of Ornithocheirus (considered by Lü et al.
[2010] as including Tropeognathus, but see Rodrigues and Kellner [2008]) + Coloborhynchus + Anhanguera. This result is
mainly based on characters related to the nasoantorbital fenestra
and dentition. In Cearadactylus atrox, the dorsal margin of the nasoantorbital opening is delimited by a thin bone bar, whereas in
Ornithocheirus, Coloborhynchus, and Anhanguera this structure
is absent (character 8). Cearadactylus atrox differs from Ludodactylus, Coloborhynchus, and Anhanguera in having a straight
ventral margin of the skull (character 11). Furthermore, the posterior margin of the nasoantorbital fenestra in C. atrox forms
a right angle, whereas in Coloborhynchus and Anhanguera it is
concave (character 22). C. atrox also lacks a dentary sagittal crest
(character 46).
The dentition also shows a distinct pattern in these closely related species. C. atrox has a dimorphodont pattern (character 48),
with the preserved rostral teeth about three times the size of the
maxillary ones. This rostral dentition is formed by less than 11
pairs of alveoli (character 51) and the maxillary teeth are small,
spaced (character 49), and laterally compressed, with a slight triangular shape (character 62). Such a combination of character
states is unique to C. atrox.
The position of C. atrox within the Ornithocheiridae as
the sister taxon to (Ornithocheirus + (Coloborhynchus + Anhanguera)) has very low support, with bootstrap values of only
3%. The inclusion of an intermediate taxon should not highly
influence this index, as has also been noted in other studies
(e.g., Penny et al., 1992; Kearney and Clark, 2003; Strauss and
Atanassov, 2006), indicating that this result should be viewed
with caution. The clade Ornithocheiridae is weakly supported
(11% bootstrap and 14% jackknife values) with Ludodactylus as
the basal taxon. Cearadactylus, however, changes position with
other species in many trees. Despite that, it always falls close
to Anhangueridae. This result contradicts the study of Unwin
(2002), in which C. atrox was regarded as the sister taxon of the
clade composed by Gnathosaurus + Pterodactylus longicollum
(Fig. 9).
Wang et al. (2009) provided the smallest data set of the three
phylogenetic proposals addressed here, being an expanded and
updated version of Kellner’s (2003) matrix. Despite the comparatively small number of characters, the topology of the consensus
tree shows high support values, with some branches having bootstrap and jackknife values above 80%. This consensus tree is very
similar to the one obtained from the data set of Andres and Ji
(2008). Cearadactylus falls out as the sister group of Anhangueridae (sensu Kellner, 2003), with ‘Ornithocheirus’ compressirostris
as the sister taxon to them (C. atrox + Anhangueridae; Fig. 10).
The support values of these branches are similar, being generally
low (15% bootstrap and 17% jackknife values).
‘Ornithocheirus’ compressirostris differs from C. atrox by lacking a premaxillary sagittal crest (character 15) and finely serrated teeth (character 48). Anhanguera piscator and A. santanae
show a foramen in the nasal process (character 21), which is absent in C. atrox. The lacrimal process of the jugal (character 23)
in C. atrox is subvertical, differing from that in closely related
taxa. The palatal ridge (character 34) of C. atrox is not as strong
as in Tropeognathus mesembrinus, being similar to that of Anhanguera. The absence of a dentary sagittal crest (character 41)
separates C. atrox from all known anhanguerids.
DISCUSSION
The high pterosaur diversity recorded from the Araripe Basin
is well known (e.g., Kellner and Tomida, 2000; Barrett et al.,
2008) and the possibility that it is overestimated has been noted
several times (e.g., Campos and Kellner, 1985; Martill and Naish,
2006; Unwin and Martill, 2007). Some have made a potential parallel with the initial stages of pterosaur studies based on material
from the Cambridge Greensand and the Solnhofen Basin, where
the great number of specimens fueled the establishment of many
taxa (Bennett, 1995, 1996; Unwin, 2001). Taxonomic reviews of
the specimens from these European deposits led several authors
to propose a reduction in the number of species present (Bennett, 1996; Unwin, 2001). Indeed, Araripe pterosaurs were first
named based on very fragmentary or incomplete specimens, potentially creating a similar scenario (Price, 1971; Wellhofer, 1977;
Kellner, 1984; Witton, 2009). Taking this into account, the holotype and only known specimen of C. atrox was compared with
other toothed pteranodontoids.
Regarding ontogeny, some sutures are not visible but the presence of unfused elements such as the right articular and both angulars suggest that the holotype of C. atrox represents a subadult
individual (Bennett, 1993; Kellner and Tomida, 2000; Ösi and
Prondvai, 2009).
The posterior limit of the nasoantorbital fenestra, forming a
straight angle with the ventral border (as already observed in the
original description; Leonardi and Borgomanero, 1985) distinguishes C. atrox from all other species. The premaxillary teeth,
however, are very different from how they were previously interpreted, due to removal of the epoxy resin that was used to enhance the fossil. Although we cannot establish the actual length
of the largest tooth, it is unlikely to have been 48 mm long as proposed by Leonardi and Borgomanero (1985) and as subsequently
followed by later studies (e.g., Unwin, 2002; Steel et al., 2005).
132
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FIGURE 10. Detail of the strict consensus tree of 240 MPTs showing the position
of C. atrox based on the modified Wang
et al. (2009) data set and clade names. A,
Pteranodontoidea; B, Anhangueridae; C, Anhanguera. Upper values are bootstraps and
the lower figures are jackknife values. Consistency index = 0.678 and retention index =
0.880 for the consensus tree.
Recently, Unwin (2002) reinterpreted several features of C.
atrox, placing this species in the Ctenochasmatidae, a conclusion followed by other authors (e.g., Steel et al., 2005; Lü et al.,
2010; Vidarte and Calvo, 2010). However, as noted above, the
mandibular symphysis of C. atrox was glued to the rest of the skull
inverted with respect to the premaxilla and, therefore, all characters related to these areas require revision. C. atrox does not
possess a rostral portion of the mandible that is more expanded
than the premaxilla (Kellner and Tomida, 2000; Unwin, 2002),
and based on the preserved parts of the jugal, quadratojugal, and
quadrate this species lacks a ‘high cheek,’ as has been proposed
for Ctenochasmatidae (Unwin, 2002; Martill et al., 2006; Bennett,
2007; Andres et al., 2010).
The tooth dimorphism is not as conspicuous as proposed by
Unwin (2002), with the largest premaxillary tooth (the 3rd)
reaching at most three times the size of the smaller maxillary
tooth (11th). Unwin (2002) also stated that C. atrox has a nonlinear pattern to the dentition, with the 5th tooth smaller than the
6th, 7th, and 8th. This relationship has not been observed by us
and, despite the premaxillary teeth being larger than the others,
the maxillary teeth diminish in size uniformly towards the posterior end. Although the dentition is similar in size to that of anhanguerids and Brasileodactylus (Kellner and Tomida, 2000) the
typical Anhanguera feature of the 5th and 6th teeth being smaller
than the 4th and 7th (Kellner and Tomida, 2000; Kellner, 2003)
is not observed in C. atrox. This species also has fewer teeth than
in all anhanguerids, with the exception of Tropeognathus mesembrinus (Wellnhofer, 1987; Kellner and Tomida, 2000).
One of the first jaws found in the Araripe Basin, Brasileodactylus araripensis (Kellner, 1984) bears many anatomical characteristics similar to C. atrox, indicating a possible systematic affinity. Both possess a groove on the dentary that is visible in ventral view and an expanded mandibular symphysis (Kellner, 1984;
Veldmeijer et al., 2005, 2009). Some differences, however, confirm that they are two distinct taxa. Among these is the spacing
between the rostral alveoli that in B. araripensis exceeds the actual diameter of the alveoli, whereas in C. atrox the reverse is
true (i.e., interalveolar spacing smaller than the alveoli diameter;
Kellner, 1984; Veldmeijer et al., 2009). Furthermore, the dentary
in B. araripensis is rather flat in its rostral portion, but this is less
evident in C. atrox. Lastly, the dentary groove reaches the rostral
tip of the bone in both taxa, but in C. atrox it terminates with a
bifurcated end.
Tropeognathus mesembrinus differs from C. atrox in having
a well-developed dentary sagittal crest, a better-developed and
deeper palatal ridge, and a less expanded distal end to the rostrum (Wellnhofer, 1987; Kellner and Tomida, 2000). ‘Cearadactylus’ ligabuei is based on an incomplete skull (Dalla Vecchia, 1993)
that might comprise a mixture of different specimens. Therefore,
Cearadactylus atrox is considered to be the only taxon of the
genus, a decision that has been proposed by other authors and
that is followed herein (Steel et al., 2005; Veldmeijer et al., 2005;
Wang et al., 2009). The main difference between Anhanguera piscator and C. atrox is the lack of a dentary sagittal crest in the latter. Unfortunately, in Anhanguera piscator the jaws are occluded
(Kellner and Tomida, 2000) and there is no information regarding the palatal ridge and dentary groove.
A pterosaur described recently from the Romualdo Formation was first published as Coloborhynchus spielbergi and later
referred to Anhanguera (Veldmeijer, 2003; Kellner, 2006; Rodrigues and Kellner, 2008). One of its most notable characteristics is the large premaxillary sagittal crest, which reaches the base
of the nasoantorbital fenestra (Veldmeijer, 2003). Anhanguera
spielbergi possesses a tooth pattern similar to C. atrox, both in
terms of tooth numbers (at least 36 versus 32–36 in C. atrox) and
distribution, with the tooth rows reaching a point level with the
middle of the nasoantorbital fenestra (Veldmeijer, 2003). Despite
these similarities, Anhanguera spielbergi differs from C. atrox in
having a well-developed sagittal crest that reaches the base of the
nasoantorbital fenestra, the presence of a dentary sagittal crest,
and in the dentary groove not reaching the rostral tip of the jaw.
Regarding the phylogenetic placement of C. atrox, reanalysis
of all three phylogenetic data sets considered above suggests that
this taxon is phylogenetically close to the anhanguerids and other
toothed pteranodontoids, although the internal organization of
these branches changes depending upon the characters and character scores constituting the original data sets. None of these
analyses recovers C. atrox as a member of the archaeopterodactyloid clade Ctenochasmatidae, contrary to the proposal of Unwin
(2002).
CONCLUSIONS
Additional preparation of the unique specimen of Cearadactylus atrox demonstrates that the rostrum was glued back to the
jaw in an inverted position, leading to several anatomical misinterpretations. Among these is that C. atrox possesses a premaxillary sagittal crest and lacks a ‘high cheek’ (contra Unwin, 2002).
Comparison with other toothed pterosaur taxa from the Araripe
Basin shows that Cearadactylus atrox is a valid taxon. Furthermore, incorporation of these new data into the data sets published by Andres and Ji (2008), Wang et al. (2009), and Lü et al.
(2010) indicates that Cearadactylus atrox is the sister group of
Anhangueridae (sensu Kellner, 2003), and is not a member of
the archaeopterodactyloid clade Ctenochasmatidae (contra Unwin, 2002).
ACKNOWLEDGMENTS
We would like to thank H. P. Silva and J. Pontes (MN/UFRJ)
for great help during preparation of the specimen; G. Oliveira
VILA NOVA ET AL.—REDESCRIPTION OF CEARADACTYLUS ATROX
(UFRPE), P. Romano (UFV), T. Rodrigues (UFES), and F.
Nunes (MN/UFRJ) for discussions regarding pterosaurs and phylogeny; L. Facó for specimen photography; M. Massarani (FFCLRP/USP) for drawings; and M. Barbosa for figure editing.
TNT is made available with the sponsorship of the Willi Hennig Society. C. Bennett, editor H.-L. You, and an anonymous
referee greatly improved the manuscript. Also we would like to
thank the Pró-reitoria de Pesquisa e Pós- Graduação (PROPESQ
proc. UFPE 23076.027497/2010-13 to J.M.S.), FAPERJ (nos. E26/111.273/2010 and E-26/102.737/2012 to A.W.A.K.), and CNPq
(no. 307276/2009-0 to A.W.A.K.). This research was partially
funded by CAPES (Masters fellowship to B.C.V.N.)
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